Wondering how a synth turns electricity into a bass, a pad or a laser zap? Synthesis means building sound from basic waveforms, then shaping it with filters, envelopes and modulation.
This guide is part of our wider look at sound design, and it covers the core ideas you need first.
| Item | Value |
|---|---|
| Most common synthesis method | Subtractive synthesis |
| Opposite of subtractive | Additive synthesis |
| Oscillators in basic FM | Two: modulator and carrier |
| Source of the sound in a synth | The oscillator |
| Envelope components in ADSR | 4 (attack, decay, sustain, release) |
Figures come from Digital Sound & Music and EDMProd.
What synthesis actually means
A synthesizer makes sound from scratch instead of recording it. Where a microphone captures a real event, a synth generates a signal and lets you sculpt it.
That is why synthesis sits at the heart of electronic music and sits beside recording-based work such as foley sound effects as a second way to get new sounds into a project.
Almost every synth, whatever its method, is built from the same few blocks:
- Oscillator: creates the raw waveform.
- Filter: removes or emphasises frequencies.
- Amplifier and envelope: controls how the volume changes over time.
- LFO: a slow modulator that moves other settings automatically.
The oscillator: where the sound begins
Subtractive synthesis starts with an oscillator, and EDMProd’s guide states that the oscillator is the source of the sound. Common shapes include sine, triangle, saw and square.
A pure sine wave has no extra harmonics, so it sounds smooth and plain. Waves such as saw and square carry many harmonics, which gives the filter plenty to work with.
Filters, envelopes and LFOs shape the tone
Subtractive synthesis is described by EDMProd as a form where parts of a harmonic-rich signal are attenuated with a filter. A low-pass filter on a saw wave, for example, removes the top end and makes the tone darker and softer.
The ADSR envelope then shapes volume over time. The same guide defines it like this:
- Attack: how quickly the sound reaches full volume.
- Decay: how quickly it drops to the sustain level.
- Sustain: the constant level while a key is held.
- Release: how long the sound fades after you let go.
A slow attack and long release suit pads and atmospheres, while very short settings give a plucky sound better suited to melodies. An LFO works much like an envelope, because it is assigned to another parameter to control it dynamically, but it repeats on a cycle.
The main types of synthesis
Digital Sound & Music says the most common method is subtractive synthesis. Learning subtractive synthesis gives you a useful vocabulary for exploring other synthesis methods. Our guide to subtractive synthesis goes deeper on that first method.
- Subtractive: start with a harmonically rich wave and filter parts away.
- Additive: build a sound by adding waves together. The same source calls it a cumbersome method that is not commonly used, even though in theory it can create any sound.
- FM (frequency modulation): one oscillator, the modulator, changes the frequency of another, the carrier. It can create sounds that are difficult to achieve with subtractive synthesis.
- Wavetable: EDMProd describes it as using morphing oscillator waves, sometimes called sample-based synthesis because wavetables come from audio samples.
Putting the methods to work
Matching a method to the sound you want
No method is better in every case. Each one makes certain jobs easy and others awkward, so it helps to match the tool to the sound in your head.
- Warm basses, leads and classic pads: subtractive synthesis is the natural fit, because you can start bright and carve the tone down.
- Bell-like, metallic or evolving tones: FM often gets there faster, since the modulator and carrier interact in ways a simple filter cannot copy.
- Textures that morph over time: wavetable synthesis scrolls through different oscillator shapes, which gives movement at the source.
- Precise control of every harmonic: additive synthesis offers it in theory, but the effort involved explains why it is rarely the first choice.
Many modern synths blend these approaches. A wavetable oscillator feeding a filter and an ADSR envelope, for instance, uses ideas from more than one method.
Why harmonics matter so much
Harmonics are the reason a saw wave sounds different from a sine wave. EDMProd’s guide compares a pure sine wave with the same signal plus added harmonics, and the second sounds richer.
That contrast explains the whole subtractive idea. You start with a signal full of harmonics, then filter out the frequencies you do not want, and what remains is your tone.
Additive synthesis works from the other direction. You begin with simple waves and add them together until the harmonic content matches the sound you want.
Using envelopes and LFOs in practice
Envelopes and LFOs are what stop a synth sounding static. Both can be assigned to a parameter, which means they are not limited to volume.
EDMProd notes that ADSR settings generally refer to a sound’s volume. You can also send an envelope to the filter, so the tone opens and closes with each note.
Here are a few typical pairings you can try:
- Pad: slow attack and long release on the amplitude envelope.
- Pluck: very short attack and release, with the filter envelope closing quickly.
- Wobble or movement: an LFO assigned to the filter, so the tone pulses on its own.
- Kick drum: EDMProd’s guide even builds one from an oscillator, an envelope and an LFO, which shows how far a few simple blocks can go.
How to start learning synthesis
Pick one synth and learn the signal path before you touch presets. Most software synths let you see the oscillator, filter and envelope on one screen.
- Choose a saw wave and play a held note.
- Lower the filter cutoff slowly and listen to the tone darken.
- Change attack and release to turn a pluck into a pad.
- Assign an LFO to the filter and hear the movement.
- Only then try FM or wavetable sounds.
Small, deliberate changes teach you more than large ones. Change one control at a time, so you know what caused each difference.
Once the basic path feels familiar, start listening to sounds you like and ask which block produced each quality. Is the brightness from the oscillator shape or the filter? Is the movement from an envelope or an LFO?
That habit of naming the cause is what turns patch-tweaking into real sound design. It also makes presets far less mysterious, because you can open one and see how it was put together.
Common beginner mistakes
- Changing many settings at once: you lose track of what each control does.
- Starting with FM: its interactions are harder to predict, so learn the simpler subtractive path first.
- Ignoring the envelope: a good oscillator and filter can still sound lifeless if the attack and release are wrong for the part.
- Treating presets as finished: adjusting one filter or envelope setting is often enough to make a patch fit your track.
Treat every patch as a small experiment. Save the ones that work, and note what you changed so that you can repeat it later.
Frequently asked questions
What is synthesis in music?
Show answer
It is the creation of sound electronically by generating a waveform and shaping it with filters, envelopes and modulation.
Which type of synthesis should a beginner learn first?
Show answer
Subtractive. Digital Sound & Music calls it the most common method and says its components carry over to other methods.
What does ADSR stand for?
Show answer
Attack, decay, sustain and release. Together they describe how a sound’s volume evolves through time.
What is the difference between an envelope and an LFO?
Show answer
An envelope shapes a parameter once per note, while an LFO cycles repeatedly. Both are assigned to another parameter to control it.
